One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10,15,11)(12,20,22,21)(13,19,14,17)(16,24,18,23)(25,26,29,33)(27,35,37,31)(28,34,30,32)(36,40,38,39)(2,5)(6,7)(9,11,15,10)(12,21,22,20)(13,19,14,17)(16,24,18,23)(25,27,29,37)(26,31,33,35)(28,36,30,38)(32,40,34,39)(9,12,15,22)(10,16,11,18)(13,24,14,23)(17,21,19,20)(26,32)(28,30)(31,39)(33,34)(35,40)(36,38)(1,3,4,8)(2,6,5,7)(12,22)(16,18)(20,21)(23,24)(25,28,29,30)(26,32,33,34)(27,36,37,38)(31,40,35,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.